MSE Seminar: Pengyang Zhao, Bridging the length scale to understand mechanical properties

Ph.D. Candidate advised by Dr. Yunzhi Wang

All dates for this event occur in the past.

264 MacQuigg Labs
105 W. Woodruff Ave
Columbus, OH 43210
United States

Mesoscale modeling of the deformation in amorphous and crystalline metals

Abstract

Plasticity in solids, both amorphous and crystalline, is a multi-scale phenomenon that requires experiments and simulations spanning over a wide range of physical lengths. Mesoscale modeling aims to bridge over the length scale from atomistic to continuum simulations by first identifying the fundamental “plasticity carrier” in the material and then utilizing it as the building block for constructing a coarse-grained model to study the deformation. This modeling scheme is applied to two types of materials, amorphous metals, commonly known as metallic glasses (MGs), and crystalline metals. In modeling MGs, the shear transformation zones (STZs) have been identified as the smallest units of plastic deformation in MGs, and are employed to formulate a kinetic Monte Carlo (kMC) model to perform STZ dynamics simulations. Experimental findings and atomistic simulation results are incorporated to model the constitutive behavior of STZs that are coupled to each other through microelasticity. Issues such as stress-strain relationships, shear band formation, local heating and the “size effect” on the strength of MGs are investigated. In the case of crystalline metals, an integrated modelling scheme of crystal plasticity (CP) and phase-field (PF) is developed to study the full-field coupling between deformation and microstructural evolution. As a demonstration, dynamic recrystallization (DRX) in polycrystalline copper is simulated and analyzed.

Bio

Pengyang Zhao received his bachelor degree of science in physics in 2009 from Fudan University in Shanghai, China. At the fall of 2009, he joined Dr. Yunzhi Wang’s group to pursue his PhD in materials science at OSU. His research focuses on modeling the mechanical deformation of materials of both amorphous and crystalline solids, in particular at mesocale that can connect the atomistic plastic events with the macroscopic mechanical properties. He has made a great effort to transfer himself from always assuming the nature as an ideal physics system to seeing it now as materials full of defects that make it more interesting.